VI. Calculating the Probability of Finding this Exoplanet

Even if a star has an orbiting planet, only in a very small
percentage of cases will that planet make a transit across the disk
of the star as seen from Earth's perspective.

The probability for a planet with a circular orbit is given by:

probability (%) =
(R_{star} / a) * 100%

where

R_{star} is the radius of the parent star in AU.
(Dividing by 215 converts solar radii to AU.)

a is the average distance the planet is
from the star, i.e., the semi-major axis of the
planet's orbit about the star, in AU.

Notes on Computing the Probability of Finding the Exoplanet

A complete derivation of the probability of finding a given
exoplanet assuming a uniform random distribution of the angle
that the plane of its orbit makes with respect to our line of
sight to the star is gven by the formula above.

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